1. Technical Field
The present invention relates to a display device, and in particular to a structure of a terminal section of a display panel to which power and signals are supplied from the outside.
2. Related Art
In liquid crystal display devices, organic EL display devices, and so on, there are formed terminal sections for supplying power, image signals, and so on from the outside. The terminal sections are connected to power supplies, signal sources, or drive circuits via, for example, flexible wiring boards. The terminal sections are exposed to the ambient air, and accordingly, reliability is an important factor therefor. Since ordinary metals are eroded by oxygen, moisture, and so on in the atmosphere, chemically stable metal oxide conductive films are used for the terminal sections, and among others, indium tin oxide (ITO) is used frequently.
When the terminals are formed from ITO, etching process is used therefor. Specifically, an ITO film is formed on the entire surface of a substrate by a sputtering process or the like, and then the ITO film is left only on pixel sections and the terminal sections.
The problem described in JP-A-11-24101 (hereinafter referred to as patent document 1) is that the ITO film remains unetched on a lower part of a step formed of a thick organic protective film formed down to the vicinity of each of the terminal sections, which causes electrical connection between the terminals. In patent document 1, measures are taken against the problem so that the residual ITO in the etching process is not caused by making the inclination of the steps gentler between the terminals.
The problem described in JP-A-9-90397 (hereinafter referred to as patent document 2) and JP-A-10-153770 (hereinafter referred to as patent document 3) is caused by the difference in the etching rate of the ITO film between on organic films and on inorganic films. Specifically, in the case in which the ITO film is used commonly for the pixel electrodes and the terminal sections, the ITO is deposited on an organic film in the pixel sections while in the terminal sections the ITO is deposited on an inorganic film. Since the etching rate of the ITO film on an organic film is higher, the ITO film between the terminal sections is not completely etched and remains accordingly. The problem described in patent document 2 and so on is a kind of a problem that the electrical connection between the terminal sections is caused by such a phenomenon. In patent document 2 and so on, the organic film is also formed between the ITO terminals so that the etching rate of the ITO deposited between the terminal sections becomes equal to that in the pixel sections, thereby preventing the electrical connection between the terminal sections.